Comparison of plant community–environment relations in two estuarine marshes of northern British Columbia

The Dala and Yakoun estuarine marshes in northern British Columbia were compared to evaluate similarities in species composition, plant communities, and vegetation–environment relationships. The Dala is a fjord-head marsh at the mouth of a glacially fed river with a fresh to brackish salinity regime and a 7-m tidal range. The Yakoun marsh is fed by lowland bog drainage on the Queen Charlotte Islands, has a salt to brackish salinity regime, and a 3-m tidal range. Both marshes contain similar dominant species (Carex lyngbyei, Deschampsia cespitosa, Potentilla pacifica, Triglochin maritimum), but share only about one third of the total (50) vascular species recorded. Four plant community types characterizing three main physiographic zones (low, intermediate, and high) were described at each marsh. Principal component analysis (PCA) of species composition data indicated similarities in general patterns of community organization at both marshes; however, PCA of soil chemical data indicated greater between-marsh differences, especially in intermediate and high zones. Canonical correlation analysis indicated that the Yakoun shows a closer connection between overall vegetation variation and substratum elevation, and a clearer elevational zonation of communities than the Dala. Examination of tidal regime data indicated that the Yakoun experiences steeper gradients in submergence time and flooding frequency than the Dala, thus offering an explanation for the different vegetation–elevation relationships.

Some aspects of the vegetation ecology of the Nanoose–Bonell estuary, Vancouver Island, British Columbia

A study of the vegetation of the Nanoose – Bonell salt marsh, Vancouver Island, British Columbia, was conducted during the period of May – September 1978. A total of 49 species of vascular plants was identified, 10 of which dominated the flora of the estuarine marsh. Six of those dominant species (Distichlis spicata, Glaux maritima, Salicornia virginica, Triglochin maritimum, Plantago maritima, and Atriplex patula) are tolerant of high salinities. Eight plant communities were identified and mapped within the study area. Aerial biomass was dominated by that of the Carex – channel edge community with a peak aboveground biomass of 1259 g dry weight/m2. Major factors affecting the occurrence and distribution of species within the marsh were salinity of the inundating water, elevation of the marsh platform, and soil texture.

Vegetation–environment relations in a brackish marsh, Lulu Island, Richmond, B.C.

A study of plant–environment relations was conducted on the foreshore marshes of Lulu Island in the Fraser River delta. Analysis of tidal records indicated that the marsh platform could be subdivided into three elevational zones: a low marsh dominated by Scirpus americanus and S. maritimus; a middle marsh dominated by Carex lyngbyei, Triglochin maritimum, and S. maritimus; and a high marsh community of Agrostis exarata, Potentilla pacifica, Distichlis spicata, and Typha latifolia. This is interpreted as a successional sequence. The low marsh experiences a maximum continuous submergence of 21–16 h, the middle marsh a maximum of 8 h, and the high marsh a maximum continuous exposure of > 200 h. ANOVA results demonstrate the overwhelming importance of elevation (Typha, Potentilla, Distichlis) and elevation–salinity interactions (Scirpus spp., Carex, Agrostis) as controls on plant distribution. In addition substrate texture and moisture content are significantly associated with variations in species abundance. The Lulu Island marshes are floristically and ecologically similar to estuarine and deltaic marshes of Washington and Oregon. Variations in vegetation and successional pattern within this group are likely a function of fluvial regimes, which influence salinity and sediment characteristics.

TRIGLOCHIN GASPENSE, A NEW SPECIES OF ARROW GRASS

A new species, Triglochin gaspense Lieth & D. Löve, is described from a salt marsh between Barachois-Ouest and Coin-du-Banc, Gaspé Peninsula, Quebec, Canada. It is distributed in Quebec, the Canadian Maritime Provinces, and Newfoundland, as well as in at least the northern part of the state of Maine, U.S.A. It is well differentiated from the other American species of the Triglochin maritimum complex, to which it belongs, morphologically (5–20 cm tall, leaves overtopping the short, few-flowered spike), cytologically (2n = 96 chromosomes), and ecologically (confined to the tidal zone of the Atlantic coast below the high-water mark). The type specimen of the new species is preserved in the Marie-Victorin Herbarium, Université de Montréal.